%0 Conference Proceedings %T BeamAggR: Beam Aggregation Reasoning over Multi-source Knowledge for Multi-hop Question Answering %A Chu, Zheng %A Chen, Jingchang %A Chen, Qianglong %A Wang, Haotian %A Zhu, Kun %A Du, Xiyuan %A Yu, Weijiang %A Liu, Ming %A Qin, Bing %Y Ku, Lun-Wei %Y Martins, Andre %Y Srikumar, Vivek %S Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers) %D 2024 %8 August %I Association for Computational Linguistics %C Bangkok, Thailand %F chu-etal-2024-beamaggr %X Large language models (LLMs) have demonstrated strong reasoning capabilities.Nevertheless, they still suffer from factual errors when tackling knowledge-intensive tasks.Retrieval-augmented reasoning represents a promising approach.However, significant challenges still persist, including inaccurate and insufficient retrieval for complex questions, as well as difficulty in integrating multi-source knowledge.To address this, we propose Beam Aggregation Reasoning (BeamAggR), a reasoning framework for knowledge-intensive multi-hop QA.BeamAggR explores and prioritizes promising answers at each hop of question.Concretely, we parse the complex questions into trees, which include atom and composite questions, followed by bottom-up reasoning.For atomic questions, the LLM conducts reasoning on multi-source knowledge to get answer candidates.For composite questions, the LLM combines beam candidates, explores multiple reasoning paths through probabilistic aggregation, and prioritizes the most promising trajectory.Extensive experiments on four open-domain multi-hop reasoning datasets show that our method significantly outperforms SOTA methods by 8.5%.Furthermore, our analysis reveals that BeamAggR elicits better knowledge collaboration and answer aggregation. %R 10.18653/v1/2024.acl-long.67 %U https://aclanthology.org/2024.acl-long.67 %U https://doi.org/10.18653/v1/2024.acl-long.67 %P 1229-1248